Method and apparatus for collecting, stacking and handling sheet material

ABSTRACT

In a preferred embodiment of the invention a conveyor means delivers sheet material to a discharge station adjacent to and above a platform on which the sheets are to be stacked. The conveyor means includes a transportation conveyor such as a shingling conveyor, a feed out roll means below the sheet material and a gate pull roll means above the sheet material. The platform means may be a roller type conveyor disposed at right angles to the shingling conveyor. Overhead pull belt means above the platform engages the upper side of sheet material issuing from the discharge station to pull the sheet material into stacked position. The pull belt means is operable to establish contact with the upper side of the sheet material before an underside of the sheet material terminates contact with the feed roll. The pull belt means maintains contact with the upper side of the sheet material until the material is in the stack to prevent any free flight of the material from the discharge station to the stack. Means are provided for sensing the stack height on the platform and a gate means at the discharge station is operative to interrupt flow of sheet material from the discharge station to the platform in response to a signal from the stack height sensing means. The last sheet out of the discharge station to complete a stack is also sensed. In response to a signal from the last sheet out sensor the overhead pull belt means is lifted, a back stop is retracted, and the roller conveyor is energized to move the stack out of the stack area. The removal of the stack from the stack area is sensed to resume normal operations.

United States Patent 1 191 DiFrank et al. i

11] 3,761,078 4 1 Sept. 25, 1973 METHOD AND APPARATUS FOR COLLECTING, STACKING AND HANDLING SHEET MATERIAL [75] Inventors: Frank J. DiFrank; Daniel Greiwe; Walter R. Skutllarek, allof Toledo, Ohio [73 Assignee: Owens-Illinois, Inc., Toledo, Ohio [22] Filed; Mar. 11, 1971 [21] Appl. No; 123,325

52 us. Cl. 271/68 Morrison 271/69 X Primary ExaminerEdward A. Sroka Atr0rneyD. T. Innis and E. J-. Holler [5 7] ABSTRACT in a preferred embodiment of the invention a conveyor means delivers sheet material to a discharge station adjacent to and above a platform on which the sheets are to be stacked. The conveyor means includes a transportation conveyor such as a shingling conveyor, a feed outroll means below the sheet material anda gate pull roll means above the sheet material. The platform means may be a roller type conveyor disposed at right angles to the shingling conveyor. Overhead pull belt means above the platform, engages the upper'side of sheet material issuing from the discharge station to pull the sheet material into stacked position. The pull belt means is operable to establish contact with the upper side of the'sheet material before an underside of the sheet material terminates contact with the feed roll. The pull belt means maintains contact with the upper side of the sheet material until'the material is in the stack to prevent any free flight of the material from the discharge station to the stack.

stop is retracted, and the roller conveyor is energized to move the stack out of the stack area. The removal of the stack from the stack area is sensed to resume normal operations.

24 Claims, 2 Drawing Figures Pmmrsussrz m 3.781.078

SHEEI 1 BF 2 BSR FIG. 1

INVENTORS FRANK J. DIFRANK DANIEL L. GREIIWE WALTER R. SKUDLARE K ATTORNEYS PATENTED 9 m3 3 sumaarz Ll LSI L2 LS3 if LSEF? SOR PRPU BACKSTOP PULL L ROLL PICKUP AIR SUPPLY fl/FVS /,/BSR @I BACKSTOP RETRACTOR ROLLER CONVEYOR DRIVE CONTROL RCDC - :FIG. 2

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- INVE NTORS FRANKJ. DIFRANK DANIEL L.GREIWE WALTER R. SKUDLAREK ATTORNEYS METHOD AND APPARATUS FOR COLLECTING, STACKING AND HANDLING SHEET MATERIAL BACKGROUND OF THE INVENTION This invention relates to improvements in apparatus for collecting, stacking, and handling material delivered in successive sheets. Although the invention will be illustrated in its application to apparatus for handling sheet material from a machine such as a corrugating machine, such apparatus being generally known as an off-bearing device, the principles of the invention are applicable elsewhere.

A corrugator delivers sheet material in such quantity as to present a serious handling problem at the discharge end of the machine. The delivered sheet material is usually collected and formed into stacks for handling and since the operation is a continuous one, there is no time available between the delivery of successive sheets in which a completed stack can be removed and a new stack started. I

Off'bearing devices in commercial use generally employ either of two solutions to this'handling problem. In one type of device two stack forming stations are provided along with a mechanism for diverting sheets delivered from the machine to either one of these stations. While a stack is being collected at one station, a previously formed stack is removed from the other station. This type of device is subject to the general disadvantage of being quite expensive because of the amount of structure and mechanism required for providing two stations and for handling stacks from each of these stations.

The other type of device operates on the general principle of providing some means for holding back the flow of sheets delivered from the machine-for an interval sufficient to permit the removal of a formed stack. A ragged stack forming operation is sometimes encountered in devices of this type because sufficient time cannot beprovided for the orderly removal of a bundle without holdingback the flow of on-coming sheets to such an extent that these sheets become disarranged. As the number of sheets delivered in a given time interval increases, this condition becomes worse with the result that this type of device definitely limits the rate at which a corrugator can be operated, either in terms of sheets per time interval or lineal feet of material per time interval.

Accordingly, it is an object of this invention to provide an improved off-bearing apparatus.

It is another object of this invention to provide an improved method and apparatus for collecting, stacking, and handling sheet material.

It is a further object of this invention to provide offbearing apparatus which produces improved squared non-interleaf bundles, increases the right angle ejecion reliability, and decreases ejection time by the use of direct sensing limit switch or other type sensors instead of using timer type cycles which waste time.

It is a still further object of this invention to provide improved off-bearing apparatus which pulls off the last few sheets and prevents any free flight of the sheets between a shingling conveyor and a conveyor at right angles thereto and thus reduces the required side ejection time. t

It is yet another object of this invention to provide a handling system which utilizes sensors to sense the exact conditions required for side ejection, thus saving time and compensating for any sheet flow interruptions. By eliminating the use of timers with a predeter- 'mined time interval for the various'operations, side head belt system to keep control of the sheets from the shingle conveyor to the stacking area and which directs and pulls each sheet to a back stop thus eliminating the need to spin off the last few sheets.

It is a still further object of this invention to provide an off-bearing device having a gate pull roll mechanism over a shingle conveyor means to keep the sheets in order when the gate at the discharge station closes to interrupt sheet flow. The gate roll pull mechanism continues the sheet flow against the back of the gate, forming a small bundle behind the gate while a sensor system detects the clearance of the last sheet below the gate to complete a stack and initiate removal of the completed stack.

SUMMARY or THE INVENTION I means engages the upper side of sheet material issuing from the discharge station to pull the sheet material into stack position. The upper side engaging means is operable to establish contact with the upper side of the sheet materialbefore an underside of the sheet material terminates contact with the delivering conveyor means at the discharge station. The upper side engaging means is operable to maintain contact with the upper side of the sheet material until the material is in the stack thereby preventing any free flight of the material from the discharge station to the stack. 4

The upper side engaging means may include a first pulley arrangement positioned above the stack area of the platform means adjacent the discharge station and a distance from the platform means which exceeds the desired stack height. A second pulley arrangement is located above the stack area of the platform means adjacent to the side of the stack area opposite the discharge station. Pull belt means is provided facing the stack area and is trained around the first and second pulley arrangements. The second pulley arrangement is supported to yieldingly urge the pull belt means toward the platform means to maintain contact with the sheet material until the material is on the stack.

Backstop means is provided adjacent the stack area on the opposite side from the discharge station for receiving the leading edges of sheet material and to define the side of a stack. The second pulley arrangement includes lower pulley means carried on a firstarm supported on the backstop means and upper pulley means carried on a second arm means extending upwardly from and secured to the first arm means. A drive pulley means is positioned above and on the other side of the backstop means from the stack area. The belt is trained around the lower pulley means of the second pulley arrangement, between the lower and upper pulley means, over the top of the upper pulley means, around the drive .pulley means and back to the first pulley arrangement to permit the backstop means to be retracted from and advanced to the stack defining position without disturbing the overhead pull belt system.

The first arm means of the second pulley arrangement may be part of a bell crank means which is operable to lift the second pulley arrangement away from a stack to permit removal of a stack from the stack area.

The first pulley arrangement may include upper pulley meansjoumaled on a fixed shaft, pivotal arm means depending from the fixed shaft, and lower pulley means journaled on a shaft carried in the depending arm means enabling the second pulley arrangement to be operable as a take-up pulley means as the rest of the parameters of the pulley system vary.

The platform means may include conveyor means, preferably a roller conveyor, disposed at right angles to the delivering conveyor means at the discharge station. The completion of a stack on a right angle conveyor means is sensed and means responsive to the stack completion sensing means is operable to drive the right angle conveyor means to remove a stack from the stack area.

Means are also provided for sensing the height of a stack on the platform means. The discharge station may include gate means responsive to the stack height sensing means for interrupting flow of sheet material from the discharge station.

The sheets of material are advantageously delivered is shingled form to the discharge station with the leading edge of each sheet overlying the preceding sheet. The gate or flowing interrupting means is actuatable into position to contact the leading edge of a sheet and thus hold back in a small bundle the sheets following the contacted sheet. The discharge station includes an underside engaging means, such as a feed roll means which functions to feed sheet material below a gateengaged sheet into the stack area. Means are provided for sensing the feed out of the last sheet not engaged by the gate means. Means responsive to the last sheet sensing means disengages contact between the upper side material engaging means and a stack of material at the stacking station. Means responsive to the last sheet sensing means retracts the backstop means away from the side of a stack to permit removal of a stack from a stack area. Means responsive to the last sheet sensing means drives the stack conveyor means to remove a stack from the stack area. Means sensing the completion'of a stack removal operation enables retraction of the gate means from a flow interruption position and resumption of normal stacking operation.

Other objects, advantages and features of this invention will become apparent when the following description is taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic view of off-bearing apparatus which embodies the teachings of this invention; and

FIG. 2 is a schematic diagram of control components connected to provide the functions desired in the invention.

DESCRIPTION OF THE PREFRRED EMBODIMENT Referring to FIG. 1 there is disclosed off-bearing apparatus in which sheets 25 of material, each preferably shingled over the sheet in front of it, are delivered by a shingling conveyor to and stacked on a roller conveyor 50 disposed at right angles to the shingling conveyor.

A discharge station is generally indicated at 30 and includes generic conveyor means indicated generally at 32. A last part 34 of a delivery or shingle conveyor, a feed out roll means 36, and a gate pull roll means 38 is considered part of the generic conveyor means at the discharge station. A discharge station drive means and housing is indicated at 37.

A gate arm 40 at the discharge station 30 is fixedly mounting on the shaft 42 of a rotary actuator which is operable to swing the arm 40 from the position shown in FIG. 1 down to engage the leading edge of a sheet issuing from the shingling conveyor 34. The gate pull roll means 38 is driven by a connection from the discharge station drive means 37 and continues to operate during this flow interruption to engage and pull up sheets to form a small bundle behind and against the gate arm 40. The shingling conveyor 34 and the feed out roll means 36 continue to rotate and engage the underside of sheets not being held by the gate 40 to discharge the remaining sheets onto the roller conveyor 50.

A limit switch LS2 is provided at the discharge station to sense when the last sheet of those not engaged by the arm 40 is discharged onto the stack on the roller conveyor 50. The limit switch LS2 may have an arm pivotally mounted on the discharge drive housing 37. The arm of switch LS2 is biased to swing toward and contact sheets issuing from the discharge station with a wide roller to contact a plurality of sheets. When no sheets remain the contact wheel and arm swing further in and close LS2 contacts in the control circuit. A stop means may be provided on the arm of the limit switch LS2 to prevent the extension of the contact wheel too far in front of sheets to interrupt their flow when the gate 40 is removed from flow interrupting position.

The right angle roller conveyor 50 has a drive indicated generally at 52. A backstop 60 is positioned on the roller conveyor 50 to receive the leading edge of the sheet material and to define the side of a stack area. The backstop 60 may be retracted from and extend to a stack defining position by an actuator indicated generally at 62. An adjustable link 64 is provided between the actuator 62 and the backstop 60 to enable selection of the size of the stack area when different size sheets are being stacked.

A limit switch LS3 is carried on the backstop 60 and is pivotally mounted and spring biased toward the stack so that the contact wheel of the limit switch assembly senses the side or edge of a stack. when the stack is removed from the stack area by the roller conveyor 50 the contact wheel moves further toward the empty stack area and closes LS3 contacts in the control circuit. A stop means on the limit switch arm prevents the arm of limit switch LS3 from pivoting sufficiently far into the stack area to receive a damaging blow from the first sheet of a new stack which is issued from the discharge station into the stack area.

An overhead pull belt means is indicated generally at 80. Although in this schematic representation only one belt and its accompanying apparatus is shown it is to be understood that a plurality of such belts may be provided to engage separate portions of the upper side of the sheet material.

A first pulley arrangement is indicated at 82 and includes an upper pulley 84 journally supported on a fixed pulley shaft 86 extending from the housing 37. An arm 88 depends from the fixed shaft 86 and joumally supports a lower pulley 90 on a lower pulley shaft 92 in depending arm means 88. The adjustable and pivotal position of the lower pulley 90 enables the pulley arrangement 82 to act as a takeup as the parameters of the remainder of the pulley system vary. The arm 88 may be spring biased to retain a desired belt tension in the system.

The pulley means 90 with the belt means 120 trained therearound performs an important squaring function for sheets leaving the shingling conveyor 34. A sheet in the shingled arrangement on conveyor 34 may arrive with its leading edge askew with respect to the direction of travel of conveyor 50 and thus also with respect to the desired stack edge defined by the backstop 60.

Accordingly, the preferred placement of pulley means 90 is such that the leading edge of a sheet 25 initially contacts the belt-pulley arrangement 120, 90 just below the center or axis of the pulley means 90. The gate pull roll 38 is still pushing the rear portion of the sheet 25 forward, and during the time that the belt 120 is slowly starting to pull the initially contacting portion of the leading edge of sheet 25 down around pulley 90, the remainder of the leading edge is brought into the desired stacking alignment by the combined pushing action of the gate pull roll 38 and the retarding action caused by the placement of pulley means 90. While the pushing of gate pull roll 38 makes the alignment correction more quickly, the preferred placement of pul ley means 90 will be able to make the alignment correction alone with certain sheet materials and other discharge station arrangements.

A second pulley arrangement iss hown at 100 and includes a lower pulley 102 journally mounted on a shaft 104 which is supported in a first arm 106 extending from and pivotally supported on a shaft 110 extending from the backstop means 60. The arm 106 may be part of a bell crank arrangement which also includes arm 108 with the shaft 110 defining the fulcrum of the bell crank. A spring means 112-yieldingly urges the pulley 102 and thus the belt train'ed therearound toward the platform receiving the sheets.

A limit switch LS1 is carried on the housing of the backstop 60 and is spring biased upwardly toward the arm 106 to obtain a measure of the stack height. As the arm 106 moves upwardly the limit switch LS1 pivots upwardly in a following movement. When roller 102 reaches a predetermined height LS1 contacts close in the control circuit.

The second pulley arrangement also includes upper pulley 114 journally supported on a shaft in the upwardly extending arm 116 which is connected to in a fixed position the arm 106.

A drive pulley 118, which is positioned on the other side of the backstop 60 from the discharge station, and a belt 120 completes the pulley system. The belt 120 is trained over the top of pulley 84; around the stack facing sides of pulleys 90 and 102; between pulleys 102, 114; over the top of pulley 114; and around drive pulley 118 back to pulley 84. This system of pulleys permits pull roll pulley 102 to maintain belt 120 in contact with the top of the stack or to be pivoted upwardly out of the way by a pull rollpick-up mechanism PRPU. The pick-up mechanism may be an air cylinder connected to the bottom of am 108 of the bell crank to lift the pull roll pulley 102 and belt out of engagement with the stack and enable removal of the stack when completed.

The pulley arrangement described also permits the retraction of the backstop 60 from the edge of the stack lized. The components can be readily located by reference to the line number where the component is tioned.

Contact switching operations may be noted in the diagram without designating a mechanical tie between the contacts and the actuating means. The contacts may be located at any convenient position even though quite remote from their actuating means. Cross reference between the actuating means and its associated contacts is easily accomplished by noting in the right hand margin of the drawing the reference character of the actuating means, for example SHR, a stack height relay, adjacent line number 10, the line in which the contact actuating relay coil is located for energization. Following the reference character the line number in which the SHR contacts appear is noted, i.e., 12. A contact line number notation that is not underlined indicates that those contacts are normally open, as in line 12. A contact line number notation that is underlined indicates that those contacts are normally closed, i.e. as the relay SOR contacts in line 15..

Leads L1 and L2 supply electrical power from a suitable power supply source. As noted hereinbefore the proper stack height is detected by the closure of limit switch contacts LS1 in line 10. The stack height relay SHR in line 10 is energized closing front contacts SHR in line 12. The gate solenoid GS in line 12 is thus energized and opens four-way valve FVl in lines 13, 14. Air from an air supply in line 18 is then supplied to a rotary gate actuator GA in line 14 to close the gate 40 in F IG.

posil to stop or interrupt flow from the shingling conveyor to the right angle roller conveyor.

The remaining sheets below the gate 40 and not engaged thereby are fed out onto the roller conveyor by the action of the shingling conveyor 34 and the feed roll means 36. The feeding of the last sheet from the discharge station is detected by limit switch LS2 which closes contacts LS2 in line 11 to energize the last sheet relay LSR in the same line. Front contacts LSR in line 15 then close to energize three separate components through closed back contacts SOR also in line 15.

First, the backstop pull roll pick-up solenoid PRS in line 15 is energized by closure of the LSR contacts to open four-way valve FVZ locatedin lines 16, 17 toconnect the airsupply in line 18 to pull roll pick-up actuator PRPU in line 17. The pull roll pulley 102 is then lifted away from the top of the stack.

Simultaneously, the backstop retractor solenoid RES in line 19 is energized by closure of the LSR contacts to open four-way valve F V3 in lines 20, 21 to connect the air supply to the backstop retractorBSR in line 21 The backstop retractor BSR pulls the backstop 60 away from the side of the stack to enable the right angle roller conveyor 50 to remove the stack from the stack area and to permit the building of a new stack.

The detection of the last sheet by closure of limit switch contacts LSR also energizes the roller conveyor drive control RCDC in line 22 to start the drive of the conveyor rollers 50 to move the bundle down a conveyor. v

As soon as the stack or bundle clears the stacking area the limit switch LS3 detects the stack removal and closes LS3 contacts in line 23 to energize stack out relay SOR. Back contacts SOR then open in line 15 to I deenergize the roller conveyor drive in line 22, deenergize the retractor solenoid RES in line 15 permitting the backstop retractor to return the backstop 60 to its stack defining position, and deenergize pull roll solenoid PRS in line 15 to permit pull roll pulley 102 to be lowered into stack building position by the actuator PRPU.

When the pull roll pulley 102 is lowered into stack building position, the limit switch LS1 detects this movement and contacts LS1 in line 10 are opened. The opening of contacts LS1 deenergizes the stack height relay SHR and opens SHR contacts in line 12 to deenergize the gate solenoid GS and actuate gate 40 out of flow blocking position to enable sheets to be fed again from the shingle conveyor 34.

The apparatus now functions in the manner described hereinbefore to deliver sheets from the discharge station to the stack area adjacent the backstop 60. The limit switch LS3 detects the arrival of sheets at the stacking position and opens to deenergize the stack out relay SOR in line 23. Back contacts SOR now close in line 15 to reset the control circuit for the nextoperation cycle.

The universal type right angle conveyors have always been a limiting corrugation production factor. The interleafing of sheets has caused the off-bearers to have to physically separate bundles before stacking. Thus the universal right angle type is usually operated one out, or in the case of two out, with an empty bundle space between bundles. The invention described herein will allow the efficient use of universal type right angle conveying systems. Not only does it improve its use for manual off-bearing; but more importantly the universal conveyor system can now be efficiently used in completely automatic off-bearing systems.

The shingling conveyor belt, the gate pull roll, the feedout roll, and the overhead pull belts all advantageously travel at the same surface speed, thus maintaining positive control and contact with no sheet slippage required. The overlapped sheets flow under the gate pull roll and then under the overhead pull belts. The leading edge of the sheet feeds under the backstop pull roll before the trailing edge of the sheet leaves the feed out roll. In this manner, the sheet is positively controlled as it is pulled squarely against the backstop. At no time does the sheet go'through an uncontrolled free fall as is the case with present equipment.

When the proper stack height is reached, the gate drops and stops the flow on the shingling conveyor. When the remaining sheets that were caught under the gate feed out, simultaneously the backstop pull roll and overhead belts are lifted from the top of the stack, the backstop retracts from the edge of the stack, and the right angle rollers start. The gate pull roll mechanism then pulls the sheets to the gate in a controlled fashion until the gate opens and the cycle starts again.

In the.past various conditions have been sensed by timers. Since timers cannot be set to exactly predict the end of each portion of the cycle, a margin of error must be allowed in each timer setting. The considerable amount of lost time becomes a limiting factor in the total cycle time, and thus limits corrugator speeds at short sheet lengths. The variable conditions are now sensed for their actual status and no time is lost in the cycle.

In conclusion, it is pointed out that while the illustrated example constitutes a practical embodiment of our invention, we do not limit ourselves to the exact details shown since modification of these details may be made without departing from the spirit and scope of this invention.

We claim:

1. Apparatus for collecting, stacking and handling material delivered in successive sheets, comprising a. a discharge station above and to one side of a stack area for receiving successively delivered sheets of material including means for'moving the material from the discharge station to said stack area,

b. alignment means above the stack area for engaging the upperside of said material and pulling it from the discharge station onto said stack area into an aligned stack position while retarding the advancement of a more forward portion of the leading edge of a sheet issuing from the discharge station enabling the pushing action on the rear portion of a retarded sheet by said material moving means at the discharge station to bring the leading edge of the retarded sheet into a desired stacking alignment,

0. stop means adjacent said stack area on the opposite side of said stack area from said discharge station, said stop means being adapted to receive the aligned leading edge of said material to define the side of a stack, i

d. said stack area alignment means engaging and maintaining contact with the upper side of said material until the leading edge of said material is engaged by said stop means thereby preventing any free flight and misalignment of said material between said discharge area and said stack area.

2. Apparatus for collecting, stacking and handling material delivered in successive sheets, comprising a discharge station above and to one side of a stack area for receiving successively delivered sheets of material including means engaging the underside of said material and moving the material from the discharge station to said stack area, and means above the stack area for engaging the upper side of said material and pulling it from the discharge station onto said stack area, and which further includes a. means for sensing the quantity of material at said stack area, and

b. means responsive to said quantity sensing means for interrupting flow of material from said discharge station to said stack area.

3. Apparatus as defined in claim 2 in which said quantity sensing means includes means for sensing height of a stack of material at said stack area.

4. Apparatus as defined in claim 2 which further includes means responsive to said quantity sensing means for removing a completed stack from the'stack area.

5. Apparatus as defined in claim 4 which further includes a. means for sensing the completion of a stack removal operation, and

b. means responsive to said stack removal sensing means for deactivating said flow interrupting means to permit resumption of sheet material flow to said stack area.

6. Apparatus as defined in claim 2 in which a. said sheets of material are delivered in shingled form to said discharge station with the leading edge of each sheet overlying the preceding sheet, and in which b. said flow interrupting means includes gate means actuatable into contact with a leading edge of sheet material.

7. Apparatus as defined in claim 6 in which a. said underside engaging means functions to feed sheet material below a gate-engaged sheet into said stack area, and which further includes b. means for sensing the feed out of the last sheet not engaged by said gate means.

8.v Apparatus as defined in claim 7 which further includes means responsive to said last sheet sensing means for disengaging contact between said upper side material engaging means and a stack of material at said stacking area.

9. Apparatus as defined in claim 7 which further in cludes a. stop means adjacent said stack area on the opposite side of said stack area from said discharge station for receiving the leading edges of said sheet material to define the side of a stack, and

b. means responsive to said last sheet sensing means for retracting said stop, means away from the side of a stack to permit removal of a stack from the stack area. 1

10. Apparatus as defined in claim 7 which further includes t a, stack conveyor means beneath said stack area for receiving material to be stacked, and

b. means responsive to said last sheet sensing means for driving said stack conveyor means to remove a stack from the stack area.

ll. Apparatus as defined in claim 7 which further includes a. means responsive to said last sheet sensing means for removing a stack from said stacking area,

b. means for sensing the completion of a stack removal operation, and

c. means responsive to said stack removal sensing means for retracting said gate means from a flow interruption position.

12. Apparatus for collecting, stacking and handling material delivered in successive sheets, comprising a. conveyor means for delivering sheet material to a discharge station adjacent to and above a platform means on which said sheets are to be stacked, and

b. means above said platform means for engaging the upper side of sheet material issuing from said discharge station to pull said sheet material into stack position,

c. said upper side engaging means establishing initial contact with the most forward portion of the leading edge of a sheet and retarding the advance thereof until the sheet is in a desired stack alignment and then forcing the sheet downwardly and under to contact the upper side of said sheet,

d. said upper side engaging means maintaining contact with said upper side of said sheet material until said material is in said stack thereby preventing any free flight of said material from said discharge station to said stack and misalignment of said sheet in the stack.

13. Apparatus for collecting, stacking and handling material delivered in successive sheets, comprising conveyor means for delivering sheet material to a discharge station adjacent to and above a platform means on which said sheets are to be stacked, and means above said platform means for engaging the upper side of sheet material issuing from said discharge station to pull said sheet material into stack position, said upper side engaging means being operable to establish contact with the upper side of said sheet material before an underside of said sheet material terminates contact with said delivering conveyor means, said upper side engaging means being operable to maintain contact with said upper side of said sheet material until said material is in said stack thereby preventing any free flight of said material from said discharge station to said stack, said upper side engaging'means including a. a first pulley arrangement positioned above the stack area of said platform means adjacent the discharge station and a distance from the platform means which exceeds the desired stack height,

b. a second pulley arrangement above the stack area of said platform means adjacent the side of said stack area opposite said discharge station, and

c. pull belt means facing said stack area and trained around said first and second pulley arrangements,

d. said second pulley arrangement being supported to yieldingly urge said pull belt means toward said platform means to maintain contact with said sheet material until said material is on said stack.

14. Apparatus as defined in claim 13 which further includes a. backstop means adjacent thestack area on the opposite side from said discharge station for receiving the leading edges of sheet material to define a side of a stack,

b. said second pulley arrangement including lower pulley means carried on first arm means extending from and pivotally supported on said backstop means, and upper pulley means carried on a second arm means extending upwardly from and secured to said first arm means,

c. drive pulley means positioned above and on the other side of said backstop means from said stack area, a t

d. said belt means being trained around said lower pulley means facing said platform means, between said lower and upper pulley means, over the top of said upper pulley means, around said drive pulley means and back to said first pulley arrangement to permit said back stop means to be retracted from and advanced to said stack defining position.

15. Apparatus as defined in claim 14 in which said first arm means of said second pulley arrangement is part of a bell crank means which is operable to lift said 5 second pulley arrangement away from a stack to permit journaled on a fixed shaft, pivotable arm means depending from said fixed shaft, and lower pulley means journaled on a shaft carried in said depending arm means enabling said second pulley arrangement to be operable as a take-up pulley means as the rest of the pulley system varies.

17. Apparatus as defined in claim 14 which further includes a. means for sensing the height ofa stack on said plat form means, and in which b. said discharge station includes means responsive to said stack height sensing means for interrupting flow of sheet material from said discharge station. 18. Apparatus for collecting, stacking and handling material delivered in successive sheets, comprising conveyor means for delivering sheet material to a discharge station adjacent to and above a platform means on which said sheets are-to be stacked, and means above said platform means for engaging the upper side of sheet material issuing from said discharge station to pull said sheet material into stack position, said upper side engaging means being operable to establish contact with the upper side of said sheet material before an underside of said sheet material terminates contact with said delivering conveyor means, said upper side engaging means being operable to maintain contact with said upper side of said sheet material until said material is in said stack thereby preventing any free flight of said material from said discharge station to said stack, said upper side engaging means further including a. a first pulley arrangement positioned above the stack area of said platform means adjacent the discharge station, and

b. pull belt means trained around said first pulley arrangement facing said stack area,

c. said first pulley arrangement including squaring pulley means positioned so that the leading edge of a sheet advancing from said discharge station initially contacts the pull belt means just below a horizontal plane through the axis of said squaring pulley means to retard the advancement of an initial contact portion of a sheet to align the leading edge of a sheet for deposition in a desired stack alignment.

19. A method of collecting, stacking and handling sheets comprising a. successively delivering sheets of material to a discharge station,

b. engaging the underside of the sheet material to move the sheet material from the discharge station to a stacking area,

c. engaging the upper side of the sheet material above the stacking area before contact with the underside is terminated and positively pulling the sheet material to a desired aligned position on said stack before terminating contact with the upper side to prevent any free flight of the sheet material from the discharge station to the stacking area,

d. retarding the advancement of a leading edge of a misaligned sheet by contacting and slowing the advancement of a more forward portion of the leading edge of a sheet issuing from the discharge station, and

e. exerting a pushing action on a rear portion of the retarded sheet to bring the leading edge of the retarded sheet into a desired stacking alignment.

20. A method of collecting, stacking and handling sheets comprising successively delivering sheets of material to a discharge station, engaging the underside of the sheet material to move the sheet material from the discharge station to a stacking area, and engaging the upper side of the sheet material above the stacking area before contact with the underside is terminated and pulling the sheet material to a stacked position before terminating contact with the upper side to prevent any free flight of the sheet material from the discharge station to the stacking area, and which further includes a. sensing the quantity of sheet material in the stack,

and

b. interrupting the flow of sheet material from the discharge station when a predetermined quantity is sensed.

21. A method as defined in claim 20 which further includes removing a completed stack from the stacking area after flow from the discharge station is interrupted.

22. A method as defined in claim 20 in which the sheets of material are delivered in shingled form to the discharge station with the leading edge of each sheet overlying the preceding sheet and which further includes a. interrupting the flow from the discharge station by engaging the leading edge of a sheet at the discharge station, and

b. forming an intermediate small bundle during flow interruption by pulling sheets advancing to the discharge station onto the top of and in alignment with the first sheet engaged when flow interruption is initiated.

23. A method as defined in claim 22 which further includes a. continuing to feed sheets below the flow interrupting engaged sheet from the discharge station to the stack area, and

b. sensing the feeding of the last sheet not engaged by the flow interruption and removing the stack of sheets from the stack area.

24. A method as defined in claim 23 which further includes a. sensing the completion of removal of a stack of sheets from the stack area, and

b. discontinuing the interruption of the flow of sheets to build another stack. 

1. Apparatus for collecting, stacking and handling material delivered in successive sheets, comprising a. a discharge station above and to one side of a stack area for receiving successively delivered sheets of material including means for moving the material from the discharge station to said stack area, b. alignment means above the stack area for engaging the upperside of said material and pulling it from the discharge station onto said stack area into an aligned stack position while retarding the advancement of a more forward portion of the leading edge of a sheet issuing from the discharge station enabling the pushing action on the rear portion of a retarded sheet by said material moving means at the discharge station to bring the leading edge of the retarded sheet into a desired stacking alignment, c. stop means adjacent said stack area on the opposite side of said stack area from said discharge station, said stop means being adapted to receive the aligned leading edge of said material to define the side oF a stack, d. said stack area alignment means engaging and maintaining contact with the upper side of said material until the leading edge of said material is engaged by said stop means thereby preventing any free flight and misalignment of said material between said discharge area and said stack area.
 2. Apparatus for collecting, stacking and handling material delivered in successive sheets, comprising a discharge station above and to one side of a stack area for receiving successively delivered sheets of material including means engaging the underside of said material and moving the material from the discharge station to said stack area, and means above the stack area for engaging the upper side of said material and pulling it from the discharge station onto said stack area, and which further includes a. means for sensing the quantity of material at said stack area, and b. means responsive to said quantity sensing means for interrupting flow of material from said discharge station to said stack area.
 3. Apparatus as defined in claim 2 in which said quantity sensing means includes means for sensing height of a stack of material at said stack area.
 4. Apparatus as defined in claim 2 which further includes means responsive to said quantity sensing means for removing a completed stack from the stack area.
 5. Apparatus as defined in claim 4 which further includes a. means for sensing the completion of a stack removal operation, and b. means responsive to said stack removal sensing means for deactivating said flow interrupting means to permit resumption of sheet material flow to said stack area.
 6. Apparatus as defined in claim 2 in which a. said sheets of material are delivered in shingled form to said discharge station with the leading edge of each sheet overlying the preceding sheet, and in which b. said flow interrupting means includes gate means actuatable into contact with a leading edge of sheet material.
 7. Apparatus as defined in claim 6 in which a. said underside engaging means functions to feed sheet material below a gate-engaged sheet into said stack area, and which further includes b. means for sensing the feed out of the last sheet not engaged by said gate means.
 8. Apparatus as defined in claim 7 which further includes means responsive to said last sheet sensing means for disengaging contact between said upper side material engaging means and a stack of material at said stacking area.
 9. Apparatus as defined in claim 7 which further includes a. stop means adjacent said stack area on the opposite side of said stack area from said discharge station for receiving the leading edges of said sheet material to define the side of a stack, and b. means responsive to said last sheet sensing means for retracting said stop means away from the side of a stack to permit removal of a stack from the stack area.
 10. Apparatus as defined in claim 7 which further includes a. stack conveyor means beneath said stack area for receiving material to be stacked, and b. means responsive to said last sheet sensing means for driving said stack conveyor means to remove a stack from the stack area.
 11. Apparatus as defined in claim 7 which further includes a. means responsive to said last sheet sensing means for removing a stack from said stacking area, b. means for sensing the completion of a stack removal operation, and c. means responsive to said stack removal sensing means for retracting said gate means from a flow interruption position.
 12. Apparatus for collecting, stacking and handling material delivered in successive sheets, comprising a. conveyor means for delivering sheet material to a discharge station adjacent to and above a platform means on which said sheets are to be stacked, and b. means above said platform means for engaging the upper side of sheet material issuing from said discharge station to pull said sheet material into stack position, c. Said upper side engaging means establishing initial contact with the most forward portion of the leading edge of a sheet and retarding the advance thereof until the sheet is in a desired stack alignment and then forcing the sheet downwardly and under to contact the upper side of said sheet, d. said upper side engaging means maintaining contact with said upper side of said sheet material until said material is in said stack thereby preventing any free flight of said material from said discharge station to said stack and misalignment of said sheet in the stack.
 13. Apparatus for collecting, stacking and handling material delivered in successive sheets, comprising conveyor means for delivering sheet material to a discharge station adjacent to and above a platform means on which said sheets are to be stacked, and means above said platform means for engaging the upper side of sheet material issuing from said discharge station to pull said sheet material into stack position, said upper side engaging means being operable to establish contact with the upper side of said sheet material before an underside of said sheet material terminates contact with said delivering conveyor means, said upper side engaging means being operable to maintain contact with said upper side of said sheet material until said material is in said stack thereby preventing any free flight of said material from said discharge station to said stack, said upper side engaging means including a. a first pulley arrangement positioned above the stack area of said platform means adjacent the discharge station and a distance from the platform means which exceeds the desired stack height, b. a second pulley arrangement above the stack area of said platform means adjacent the side of said stack area opposite said discharge station, and c. pull belt means facing said stack area and trained around said first and second pulley arrangements, d. said second pulley arrangement being supported to yieldingly urge said pull belt means toward said platform means to maintain contact with said sheet material until said material is on said stack.
 14. Apparatus as defined in claim 13 which further includes a. backstop means adjacent the stack area on the opposite side from said discharge station for receiving the leading edges of sheet material to define a side of a stack, b. said second pulley arrangement including lower pulley means carried on first arm means extending from and pivotally supported on said backstop means, and upper pulley means carried on a second arm means extending upwardly from and secured to said first arm means, c. drive pulley means positioned above and on the other side of said backstop means from said stack area, d. said belt means being trained around said lower pulley means facing said platform means, between said lower and upper pulley means, over the top of said upper pulley means, around said drive pulley means and back to said first pulley arrangement to permit said back stop means to be retracted from and advanced to said stack defining position.
 15. Apparatus as defined in claim 14 in which said first arm means of said second pulley arrangement is part of a bell crank means which is operable to lift said second pulley arrangement away from a stack to permit removal of a stack from the stack area.
 16. Apparatus as defined in claim 14 in which said first pulley arrangement includes upper pulley means journaled on a fixed shaft, pivotable arm means depending from said fixed shaft, and lower pulley means journaled on a shaft carried in said depending arm means enabling said second pulley arrangement to be operable as a take-up pulley means as the rest of the pulley system varies.
 17. Apparatus as defined in claim 14 which further includes a. means for sensing the height of a stack on said platform means, and in which b. said discharge station includes means responsive to said stack height sensing means for interrupting flow of sheEt material from said discharge station.
 18. Apparatus for collecting, stacking and handling material delivered in successive sheets, comprising conveyor means for delivering sheet material to a discharge station adjacent to and above a platform means on which said sheets are to be stacked, and means above said platform means for engaging the upper side of sheet material issuing from said discharge station to pull said sheet material into stack position, said upper side engaging means being operable to establish contact with the upper side of said sheet material before an underside of said sheet material terminates contact with said delivering conveyor means, said upper side engaging means being operable to maintain contact with said upper side of said sheet material until said material is in said stack thereby preventing any free flight of said material from said discharge station to said stack, said upper side engaging means further including a. a first pulley arrangement positioned above the stack area of said platform means adjacent the discharge station, and b. pull belt means trained around said first pulley arrangement facing said stack area, c. said first pulley arrangement including squaring pulley means positioned so that the leading edge of a sheet advancing from said discharge station initially contacts the pull belt means just below a horizontal plane through the axis of said squaring pulley means to retard the advancement of an initial contact portion of a sheet to align the leading edge of a sheet for deposition in a desired stack alignment.
 19. A method of collecting, stacking and handling sheets comprising a. successively delivering sheets of material to a discharge station, b. engaging the underside of the sheet material to move the sheet material from the discharge station to a stacking area, c. engaging the upper side of the sheet material above the stacking area before contact with the underside is terminated and positively pulling the sheet material to a desired aligned position on said stack before terminating contact with the upper side to prevent any free flight of the sheet material from the discharge station to the stacking area, d. retarding the advancement of a leading edge of a misaligned sheet by contacting and slowing the advancement of a more forward portion of the leading edge of a sheet issuing from the discharge station, and e. exerting a pushing action on a rear portion of the retarded sheet to bring the leading edge of the retarded sheet into a desired stacking alignment.
 20. A method of collecting, stacking and handling sheets comprising successively delivering sheets of material to a discharge station, engaging the underside of the sheet material to move the sheet material from the discharge station to a stacking area, and engaging the upper side of the sheet material above the stacking area before contact with the underside is terminated and pulling the sheet material to a stacked position before terminating contact with the upper side to prevent any free flight of the sheet material from the discharge station to the stacking area, and which further includes a. sensing the quantity of sheet material in the stack, and b. interrupting the flow of sheet material from the discharge station when a predetermined quantity is sensed.
 21. A method as defined in claim 20 which further includes removing a completed stack from the stacking area after flow from the discharge station is interrupted.
 22. A method as defined in claim 20 in which the sheets of material are delivered in shingled form to the discharge station with the leading edge of each sheet overlying the preceding sheet and which further includes a. interrupting the flow from the discharge station by engaging the leading edge of a sheet at the discharge station, and b. forming an intermediate small bundle during flow interruption by pulling sheets advancing to the discharge station onto the top of and In alignment with the first sheet engaged when flow interruption is initiated.
 23. A method as defined in claim 22 which further includes a. continuing to feed sheets below the flow interrupting engaged sheet from the discharge station to the stack area, and b. sensing the feeding of the last sheet not engaged by the flow interruption and removing the stack of sheets from the stack area.
 24. A method as defined in claim 23 which further includes a. sensing the completion of removal of a stack of sheets from the stack area, and b. discontinuing the interruption of the flow of sheets to build another stack. 